The present invention is a modified Rankine cycle steam engine employing a jet pump to recirculate spent steam. The prior art contains disclosure of specific jet pump designs, disclosure of jet pumps and condensers used in an unmodified Rankine cycle engine, and disclosure of a non-condensing Rankine cycle engine. A need exists for a simple, efficient steam engine which does not employ a condensing unit.
A collection of devices of the type known in the prior art is found in the Official U.S. Patent Office Classification of Patents, particularly in class 60, subclasses 65, 92, and 107. Examples of such devices are found in U.S. Pat. Nos. 3,686,867; 3,314,236; 1,982,060; and 1,668,927.
Hull U.S. Pat No. 3,686,867 has regenerative feed heaters which operate on portions of steam withdrawn from initial turbine stages and water from the condenser.
Zanoni U.S. Pat No. 3,314,236 employs a jet pump driven by energy remaining in steam portions exhausted from initial turbine stages to reheat and drive water from a condenser toward the boiler. Zanoni teaches the use of tandem combinations of jet pumps.
McCallum U.S. Pat No. 1,982,060 is an example of the use of a "steam-water" feed pump for increasing pressure to the boiler.
Stumpf U.S. Pat No. 1,668,927 describes the use of steam exhausted from one cylinder of a piston engine to draw steam from other cylinders. Stumpf particularly notes that he uses no condenser; the working fluid remains in a gaseous state while passing through the engine and is discharged when spent rather than recirculated.
A need exists for easily fabricated steam handling system which reduces the exhaust line pressure of an expansion engine and recirculates the spent steam to the boiler where it is reheated.